Fuse plug of regenerable type



Jan. 4, 1949. R. JQPERALTA FUSE PLUG OF REGENERABLE TYPE Fiied Aug. 20, 1947 nvmvrozz Ruse-emf PEQAL TA BY E0 fi m m,

, A7mQA/y5 Patented Jan. 4, 1949 FUSE PLUG OF REGENERABLE TYPE Roberto J. Peralta, Mexico City, Mexico Application August 20, 1947, Serial No. 769,713

In Mexico February 26, 1947 7 Claims. (Cl. 200-125) The present invention relates in general to electric fuse plugs, and in particular to some new and useful improvements in plugs of this kind which are of the regenerable type, being wholly different from those which so far have been known as will become apparent in the course of the following description. Before giving a specific description of the device as illustrated in the attached drawing, it is necessary to consider some conceptions concerning the essential conditions and regulations that this class of electric articles must meet.

One of the essential safety conditions required for the acceptance admission of a fuse plug of the regenerable type, is that said plug proves to be absolutely safe against blow out flames generated on the fusion of any part of the fuse element upon its failure to resist an overcharge of electric current. Another condition requisite to approval is, that there must exist an absolute contact between the fuse element and the electric contact terminals in order to avoid the formation of arcs. Another essential condition is that these articles be designed in such a way that, it be absolutely necessary to remove the plug from the socket or similar medium where it is placed in a circuit for replacement or regeneration of the fusible elements. Besides these conditions others are more or less imperative for a fuse plug of the type referred to in the present invention. For example, one other prerequisite is the absolute hermetic nature of the said plugs, for the purpose of avoiding also the escape of the gases formed upon melting of a fusible element thereof.

In plugs for similar use referred to in other patents of mine, there is employed a tablet, which like a star lodges a number of fusible elements each adapted to take an independent contact, and consequently to be placed in arbitrary order for the purpose of having a regenerable fuse offering a certain number of elements for substitution at a given moment when one of the said fuse elements is melted. Nevertheless I have found in the said plugs a series of difliculties, which, although they are not against the established regulations, still involve impediments and characteristics little desirable in products which it is intended to deliver to the consuming public with complete guaranties. Therefore, after much trial and experimentation I have succeeded in providing a fuse of the type described combining all the goodconditions desirable and essential for this class of articles.

For the purpose of outlining the nature of the invention the latter contemplates the provision of a hollow principal body of dielectric material, preferably of a thermosetting plastic, such as phenolic plastics or the like. The said body has an upper enlargement and a lower reduced portion arranged in such a way that on the reduced portion a threaded cap is superimposed and filletted on the outside and inside of the widened portion there is placed the tablet carrying the multiple fusible elements. A cap covers the said enlargement and a screw axially penetrates from the bottom of the reduced portion of the aforementioned body up to the central part of the cap into which it is screwed. When tightened, the screw causes a pressing adjustment of the said cap against the tablet by means of a flat contact spring, and at the same time the cap referred to is pressed tightly against the end of the widened portion of said body.- Under these conditions, since a metallic feather or contact carried by the said filleted cap is pressed into contact with one of the lower ends of the fusible element carried in the said tablet, the aforementioned spring presses this end against said metallic feather or contact and provides a secure electrical joint under a very considerable pressure, and in this manner it meets the desired safety conditions referred to. Moreover, since the axial screw tightens the cover against the end of the enlarged portion thereby completely closing the open upper part of the body, and the said screw at the other end is provided with a conical finish and an enlarged head, it thus operates to provide an hermetic seal, and avoid all possibilities of the escape of smoke or flame.

One of the most detrimental results which have been observed in some other forms of regenerable fuses invented by me, is that, when an overcharge occurred and the element melted precisely in the portions calculated for a determined passage of amperes, the flame jet resulting occasioned the melting of the adjacent fusible parts, finally insulating some of the prongs or projections of the fusible star. The corresponding undesired destruction which resulted in inoperability of said adjacent elements, which of course, was an undesirable result for the public.

Objects and features of the invention are to provide regenerable type fuse plugs of the charv The characteristic details of the present inventapered or frustro-conical portion 54. 'Therim 53 pressing against the portion 25 functions as an hermetic seal and the conical body 54 to which the screw is secured as by a small deformed portion 41a in the screw and a head 55 closes the opening it in the bottom portion l3 of the body It]. To avoid the need for a screw driver, the portion 4| 2) of the screw just below the head 55 is substantially square in section and fits into a square recess 5lb in the conical body 54 so that when the screw is secured in place by the deformed or riveted portion Me, the screw will rotate upon rotation of head 5|. No screw driver will be required. The head 55 of screw 4! functions as a contact part to contact with one current terminal of a socket (not shown), while the metallic threaded cap 24 makes contact with the other socket terminal. In these conditions, and after the parts have beenpositioned for assembly in the manner shoWn in Fig. 1, the screw M is screwed into nut 48, and the flat spring part 49 makes contact with the nut 48 and the screw 4!, while the other loose leg 49a makes contact by pressure with the star-like portion 31 of the fusible element 35 and through one of the prongs 34, by means of its bends 42 and 43 closes the electric circuit making contact with the part 2! of member 22 and the metallic cap 24, placing the fusible element 35 in series with the terminals in the socket (not shown). When an overload of current causes the particular prong 34 to fuse, the flame or gases developed are prevented from escaping by the hermetic seals provided between the separable parts of the device. To reset the device for use, it is necessary to remove the entire plug in from the socket and thereafter to unscrew the screw 4| from nut 48 and remove the cover 45 from the cylindrical portion II. The tablet 26 is then removed and rotated to bring a fresh one of the prongs 34 of element 35 into position for engagement with the contact part 2!. The parts are then reassembled and the plug screwed back into the socket. Since the entire plug must be removed from the socket, for such purposes, dangers of electric shock are eliminated.

While a practical and preferred form of putting the invention into practice has been described, I wish to make it clear that it is not my purpose to limit my rights exclusively to the constructions and specific disclosures shown and described, because in the industrial application changes and modifications within the spirit and scope of the claims defining the invention are possible and are contemplated. Therefore, the limitations in practice should only be bounded by the scope of the claims appended hereto.

What is claimed is:

1. Improvements in fuse plugs of the regenerable type comprising a principal hollow body, a metallic threaded cap mounted on said body, a contact member electrically connected to said cap and extending into said body, said body having an open end, a multiple fuse bearing tablet member removably carried in said body. a multiple fuse mounted on said tablet member, said fuse having a plurality of prong-like parts and central part, a cover removably mountable on said body over said open end, a contact spring carried by said cover and engageable with said central part of said fuse, a screw member for securing said cover member to said body, said screw member serving to draw said cover onto said body and thereby to press said spring against said central part of said fuse and, also, to press member to complete an -6 one of said prong-like parts against said contact electrical series circuit,

when said screw is loosened and tightened.

2. Improvements in fuse plugs of the regenerable type comprising a principal hollow body, a removable tablet-like member, a multi-pronged fusible element carried by said tablet-like member, a removable cover for said body, an axially extending screw for securing said cover to said body, a contact member secured to said cover for engaging said fusible element, a metallic threaded member positioned on said body,

protuberances upon said body to prevent rotation of said threaded member, a contact strip electrically secured to said threaded metallic member and extending into said body for contact with one of the prongs at a time of said fusible element, and said screw being in electrical contact with said contact member.

3. Improvements in fuse plugs of the regenerable type comprising a principal hollow body, a removable tablet carried Within said body, a multi-pro-nged fusible element mounted on said tab-let, contacts for electrically connecting one of the prongs of the fusible elements at a time in an electrical circuit, a removable cover for said body and an axially extending screw for securing said cover to said body, a threaded metallic cap mounted externally of said body, and said body having an annular opening in one end defined by a ledge, protuberances on said ledge, and said cap having portions fitted on said ledge about said protuberances to prevent rotation of said metallic cap relative to said body, one of said contacts being electrically connected to said metallic cap and extending into said hollow body for contact with one of said prongs at a time and a second of said contacts being mounted on said cover for engagement with said fusible element, said second of said contacts being electrically connected with said screw.

4. Improvements in fuse plugs of the regenerable type comprising a principal hollow body, a threaded metallic cap mounted on said body, a removable tablet carried by said body, a multipronged fusible element mounted on said tablet, contacts for electrically connecting one of the prongs of said fusible elements at a time in an electrical circuit including said cap, a removable cover for said body, an axially extending screw for securing said cover to said body, a striated head of dielectric material for said screw, and a conical sleeve portion of dielectric material for said screw for providing a sealing joint with an opening defined by portions of said body for sealing the opening, said head also having a sealing portion engageable with a surface of said metallic cap adjacent said opening.

5. Improvements in fuse plugs of the regenerable type comprising a principal hollow body, a conductive cap mounted on said body, a removable tablet carried by said body, a multi-pronged fusible element mounted on said tablet, contact means for electrically connecting one of said prongs at a time in an electrical circuit including said cap, a removable cover for said body, a screw for securing said cover to said body, said tablet being substantially cylindrical and having a recess in one end face and radially distributed holes into each of which one of the prongs extends, and having a peripheral edge and a beveled edge around which portions of said prongs are bent, said fusible element having a portion fitted within said recess, a heat resisting washer underlying said element within said recess, and an insulating washer overlying said element and aligned with said first-named washer to protect said element :trom name developed upon fusion of any of said prongs.

6. Improvements in regenerab'le fuse plugs as per claim 4, in which said conical sleeve portion of dielectric material is secured to said screw as by a deformed portion.

'7. Improvements in :fuse plugs of the regenerable type comprising a principal hollow body of dielectric material, a metallic threaded cap positioned on said body externally thereof, a contact member electrically connected to said cap and extending into said body, said body having an open end, a multiple .fuse bearing tablet member removably carried in said body, a multiple fuse mounted on said tablet member, said fuse having a plurality of prong-like parts and a central part, a cover of dielectric material removably mountable on said body over said open end, a contact spring secured to said cover and engageable with said central part of said fuse, a metallic screw member for securing said cover member to said body, said screw member being electrically connected to said contact spring, said screw member serving when tightened to draw said cover onto said body and to 8 press said contact spring against said central part of said fuse and, also, to press one of said prong like parts against said contact member to complete an electrical series circuit, rotation preventing means within said body engageable with said tablet member, and additional interengagin'g rotation-preventing means on said body and on said cover whereby rotation is prevented both of said tablet member and of said cover both when said screw is loosened and tightened, said body, also, having external protuberanes in :a portion thereof and said metallic cap having port-ions fitting about said protuberances to prevent rotation of said metallic cap relative to said body.

ROBERTO J. PERALTA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 809,300 H'epke et a1 Jan. 9, 1906 5 1,316,331 Rogerson Sept. 16, 1919 1,475,200 Terrell et a1. Nov. 27, 1923 1,567,187 Lay Dec. 29, 1925 2,401,958 Peralta June 11, 1946 

